Robust Optical Detection of Ga³⁺ by a Rhodamine- and Coumarin-Based Proficient Probe: Theoretical Investigations and...

Area of Science:

• * Chemical Sensing and Molecular Probes
• * Coordination Chemistry
• * Bioimaging and Cellular Assays

Background:

• * Accurate detection of metal ions like Gallium (Ga³⁺) is crucial in biological and environmental studies.
• * Development of selective and sensitive fluorescent probes is essential for real-time monitoring of metal ions.
• * Existing methods often lack selectivity or require complex sample preparation.

Purpose of the Study:

• * To design and synthesize a novel rhodamine-B- and coumarin-based fluorescent probe for selective Ga³⁺ detection.
• * To investigate the sensing mechanism, binding stoichiometry, and detection limits of the probe.
• * To evaluate the probe's applicability in live-cell imaging and intracellular tracking of Ga³⁺.

Main Methods:

• * Synthesis of a rhodamine-coumarin based ligand.
• * Structural characterization using Single-Crystal X-ray Diffraction (SC-XRD).
• * Spectroscopic analysis (fluorescence, mass spectrometry, Job's plot, NMR titration).
• * Computational studies (DFT, TD-DFT).
• * Live-cell imaging experiments in HaCaT cells.

Main Results:

• * The probe exhibits high selectivity for Ga³⁺ over other metal ions with a nanomolar detection limit.
• * SC-XRD and solution studies confirmed the binding stoichiometry and the spiro ring-opening mechanism for fluorescence enhancement.
• * The probe demonstrated a reversible response in the presence of pyrophosphate.
• * Successful live-cell imaging and intracellular tracking of Ga³⁺ in lysosomes were achieved.
• * Computational studies provided insights into the electronic properties and energy levels of the probe and its complex.

Conclusions:

• * The developed rhodamine-coumarin probe is an efficient tool for selective and sensitive detection of Ga³⁺.
• * The probe's mechanism involves a Ga³⁺-induced spiro ring opening, leading to a turn-on fluorescence response.
• * The probe shows significant potential for bioimaging applications, enabling intracellular Ga³⁺ visualization.
• * This work contributes a valuable method for studying Ga³⁺ in biological systems.